Drier



y 939. R. SKAGERBERG 2, 66,379

DRIER Filed March 12, 1936 2 Sheets-Sheet 1 lzazt'iuer' Sifayeherg A M Iy 1939- R. SKAGERBERG 2,166,37

DRIER Filed March 12, 1936 2 Sheets-Sheet 2 Butcher Slfagerbery A A MPatented in, 1a, was 2,166,379

UNITED STATES PATENT OFFICE DRIER ButcherSkagerberg,8t.laul.lllnn.,adgnorto The Brown Instrument Company.Philadelphia,

Pa., a corporation of Penmylvanla Application March 12, 1988, Serial No.68,808

10 Claims. (01. 34-48) This invention relates to drying machines in noaccurate control of the hot air for drying general and more particularlyto those types of purposes has been provided. drying machines commonlyknown as continuous I ilnd that by varying the volume or temperadrierssuch as are used in paper mills, textile ture or both of the air thusapplied to paper mills, etc. driers, there is an instantaneous response.In 5 It is common in the art to provide continuous other words, it the vlum r temperature 18 redriers in paper mills with hollow rolls overwhich duced the drying eflect is immediately reduced the paper web isled to be dried. These rolls are and the paper becomes damp. If thevolume or heated to cause the drying action, the heating temperature isincreased the paper immediately J medium usually employed being steam.It is debecomes more dry.

sirable in the process of paper making that It is therefore the primeobject of this inventhe paper be dried to within close limits of apretion to provide an automatic control system for determined moisturecontent. There is a tenda drier wherein the majority of the dryingaction ency for the paper web to vary in moisture is obtained by thesteam drier rolls, wherein the 5 content when it comes off the drier.These varlsmaller portion of the drying action is obtained ations may becaused by variations in the room by the hot a d y g ans, wherein t edrying atmospheric condition, the thickness of the paper effect of thesteam drier rolls is maintained subweb entering the drier, the operationof the stantially con tant n wher in the ry n efi ct presses and thecondition of the press felts which of the hot all means is varied inaccordance with precede the drier, and the nature of the stock var a onsin e moistu e con e o th p p used in making the paper web. web as iteaves the drier rolls.

It has been the practice in the past to attempt It is another object ofthis invention to provide to control the moisture content of thefinished 9' dr utilizing steam rolls and air blasts for paper bycontrolling the steam applied to the 7 8 -lbe a s fed Over the s emsteam drier rolls. Various methods of controlrellerwherein the heatntent Of he Steam in ling this steam have been employed, some of thesteam rolls is maintained substantially conwhich are maintainingconstant pressures or temeht f C v n e in a d wherein the yperatures inthe steam drier rolls, which presins e e 0f t e is va ed in reeliohee t0the sures or temperatures are adjusted by the opermoisture content ofthe substance being dried, ator or which pressures and temperatures arewhereby t substance is dried to Dredetercontrolled by suitable detectorsresponsive to the mined degree regardless of its condition as itmoisture content of the paper web as it leaves n rs he drierthe drier.These control systems have their A further Object of this invention i toprovide shortcomings due to their particular principles 8 drierembodying stem 1 eans ve w ich of operation. In these systems it isdiflicult to the substance to be dried is fed, the heat conmaintainaccurate control of the moisture content which and whsequehtly the d yng action tent since the steam drier rolls must be constructwhich ismaintained Substantially t ted of 'a considerable thickness to withstandcen- A f r Object of this invention i pr vide trifugal force and steampressure, and this thicka drier in which an air blast is directed at or0 ness retards the transmission of heat to the paper heal the surface 0!the substance t0 be dried. the 40 web. Therefore, when a detector orcontroller drying eflect the ll being Varied c dcalls for increasing orreducing the drying eflfect mg to "M1095 the moisture content of thethere is a considerable lag or loss of time before substance to bedriedthe action of the steam is felt again at the deother objects andadvantages will become tector or controller. This type of control syssto those skilled in the art upon reference tom, therefore, involvingsimply the control of to t e accompanying specification claims anddrawings in which drawings: the steam valve supplying steam to the steamFig 81mm] drier rolls is unable to control the moisture con- 0 1 a aucillustration of my tent of the paper web within very close limits. m z gz g ig mgf ggfig g a It has also been the Practice in the Past todrinier drier with my invention applied thereto;

employ hot air as an xilia y mean of ry n Figure 3 is a sectional viewtaken substantially paper. The use of this hot air provides addion line3.4 of Figure 2.

tional drying capacity over and above that which Referring now to-Figure 1, l0 designates the 5 is provided by the steam drier rolls.However, paper web coming from conventional press rolls CJI II and II ofthe forming end of a paper machine. The web 'll passesoveran idler rollit and then over the steam drier roll it of the Yankee drier. From thereit passes over idler rolls II, II, I! and I8 to a calendar stack, notshown.

Heating fluid which may take the form of steam is supplied through apipe 2| under the control of a valve ll to thedrier rolls l4 toheat theroll I and thereby accomplishing a drying action on the paper web II.The valve ll may be operated by a proportioning motor H which may be oithe type shown and described in Patent 1,989,972, issued to Louis L.Cunningham on February 5, 1935. Condensed steam may be drawn from thedrier roll II by means of a pipe 23.

Power may be supplied to the proportioning motor 22 by means oi. linewires 2' and 28 leading from some source of power not shown. Theproportioning motor 22 may be positioned in any number of a plurality ofpositions by means of a controller, generally designated at 21. Thiscontroller 21 may comprise a bellows II for operating a slider 28 withrespect to a potentiometer coil 3., the potentiometer coil 8| beingconnected by wires Ii and 32 and the slider I. being connected by a wire33 to the proportioning motor 22. If it be desired to operate thecontroller 21 in accordance with temperatures in the drier roll I, thebellows 2! may be connected by a suitable capillary 35 to a bulb, notshown, containing a volatile fill and located in the drier roll I l. Thearrangement is such that as the steam presure or temperature increases,the slider 29 is moved upwardly with respect to the potentiometer coil3. to operate the proportioning motor 22 to position the valve 2!towards a closed position. Likewise, a decrease in steam pressure ortemperature causes movement of the slider 20 downwardly with respect tothe potentiometer coil 30 to operate proportioning motor 22 to movevalve 2| towards an open position. In this manner the valve 2| ispositioned in accordance with steam pressures or steam temperatures tomaintain the heat content of the drier roll I substantially constantand, therefore, the drying effect of the drier roll I is maintainedsubstantially constant. While I have illustrated in this embodiment ofthe invention the potentiometer slider 28 as being actuated by atemperature responsive device it is to be understood that this slidermay be actuated by changes in pressure of the steam if so desired.

In order to cause drying of the paper web II by means of an air blast, Iprovide on a Yankee drier a hood 3! over the drier roll ll, the hood 31receiving a supply of heated air from a fan 38 which may be driven byany suitable means, such as a pulley 38. Fan 38 receives air from aradiator or heat exchanger ll. Heating fluid, which may take the form ofsteam, may be supplied to the radiator I by means of pipes ll. The hoodI1 is provided with openings or tuyeres 42 for causing the air forcedinto the hood 31 to impinge upon the surface of the paper web Ill andthereby cause a further drying action on the paper web ll. Moistureladen air is drawn oil. the paper web i. through a passage 43 by meansof a fan 44 which may be driven by any suitable means, such as a pulleyll.

The supply of steam to the heat exchanger or radiator 4| may becontrolled by a valve 4 which in turn may be positioned in any number ofpositions by a proportioning motor 41, which may also tats the formshown and described in the above referred to Cunningham patent. Powerissuppliedtotheproportioningmotorflbymeam of line wires 40 and u leadingfrom some source of power, not shown. The proportioningmotorllm'aybeconnectedbywiresllsndll to a potentiometer coil." and by awire II to a slider l4 cooperating with the potentiometer coil II, athree pole double throw switch 41" belnginterposedinthesewiresasshown.The variablepotentiometer is controlled by a controller, generallydesignated at I, which may be of any type responsive either directly orindirectly to the moisture content oi. the paper web II as it leaves thedrier roll H. For purposes of illustration, I have shown this controllerII to be of the tension roll type. The slider I4 is carried by a pivotedlever ll pivoted at 51. The lever It carries a roll II which engages thesurface oi the paper web II and this roll II is urged in a clockwisedirection by means of an adJus-table weight ll. As the moisture contentof the paper web ll increases, the paper web ll expands and allows theweight II to move the slider 54 downwardly with respect to thepotentiometer coil l8.

, This downward movement causes operation of the proportioning motor 41to move the valve ll towards an open position to increase thetemperature of the air blast impinging the surface oi the paper web IIto increase the drying action thereof. As the moisture content of thepaper web ll decreases, the paper web ll contracts to operate the slider54 upwardly with respect to the potentiometer coil 53 against the actionof the biasing weight is. This upward movement of the slider 54 causesoperation of the proportioning motor 41 to move the valve 46 towards aclosed position to decrease the temperature of the air blast impingingthe paper web II to decrease the drying action thereof.

From the above it will be seen that I have provided a control systemwherein the majority of the drying action is performed by the drier rollII and the drying action of this drier roll I is maintainedsubstantially constant. Any variations in the moisture content of thepaper web Ill leaving the drier roll I aifects the moisture responsivecontroller 55 to control the temperature of the air blast impinging thepaper web ii to increase or decrease the drying action thereof tomaintain the moisture content of the paper web Ill leaving the drierroll I substan-' tially constant at all times.

In order to control the drying action of the air blast by controllingthe volume of air impinging the paper web l0 instead of by controllingthe temperature of the air, the speed of the fan may be varied or avolume damper may be provided between the fan 18 and the hood 31. Forpurposes of illustration, I have shown a volume damper ii for thispurpose. This volume damper 6| may be variably positioned by means of aproportioning motor ll' which is, in all respects, similar to theproportioning motor 41. Power may be supplied to the proportioning motor41' by means of line wires 48' and 4! leading from some source of power,not shown. Proportioning motor 41' may be connected by wires II, I and52' to switch 41", which when moved to its downward position connectsthese wires to wires i0, BI and 52 respectively and hence to thepotentiometer of the moisture responsive controller '5. The arrangementis such that as the moisture content of the paper web ll leaving thedrier roll ll increases, the volume damper I is operated to increase theiiow of air and, likewise, if

the moisture content of the paper web II de- 7cresseathevolumedamperliisposltionedtothisheatedaircausingadryingactiononthe decrease the flow of drying air.From the foregoing, it should be apparent that the drying effeet of theair may be controlled by varying either its temperature or quantity, andthat either the temperature controller or the volume damper may beemployed for controlling the drying eilect by moving switch 41" to thedesired position. If it be desirable to control both the volume ofdrying air and the temperature thereof, the proportioning motors l1 and41' may both be used to accomplish this mode of operation. This may bedone by bridging the oppositecontacts of switch 41" or by omitting thisswitch entirely.

Referring now to Figures 2 and 3, I have shown my invention as appliedto a Fourdrinier drier. The paper web leading from the forming end of apaper mill is generally designated at 88 and this paper web is passedover drying rolls 88 and a spring roll 81 to a calender stack 88. Thepaper web 85 is held against the upper drying roll 88 by means of a felt88 suitably guided by guide rolls II. The paper web 85 is also heldagainst the lower drying roll 88 by a felt II suitably guided bymeans'of guide rolls I2.

Heating fluid which may take the form of steam is supplied to a headerI4 under the control of a valve I5 which may be positioned by aproportioning motor I8 which also may be of the type shown and describedin the above referred to Cunningham patent. Power is supplied to thisproportioning motor I8 by means of line wires I1 and I8 leading fromsome source of power, not shown. Steam is delivered from the header Itby means of pipes 19 to each drier roll 88 to perform the drying action.

The proportioning motor 16 may be adjustably positioned by means of acontroller, generally designated at 88, and which may comprise a bellows8| for operating a slider 82 with respect to a potentiometer coil 08.The potentiometer coil 88 and slider 82 are connected to theproportioning motor I8 by wires 84, 85 and 86 respectively. If it bedesired to operate the controller 80 in accordance with steam pressuresin the header I4, the bellows 8i may be connected by a pipe 81 to theheader It. If it be desired to operate the controller 80 in accordancewith the temperature of the drying rolls 66, the bellows 8| may beconnected by a capillary tube to a bulb containing a volatile fill andlocated in any one of the drying rolls 68. The arrangement is such thatas the steam pressure or temperature increases, the slider 82 is movedupward with respect to potentiometer coil 83 to operate proporthe felts59 and II form pockets which intrap moisture laden air which retardsmaterially the drying action on the paper web 55. It is, therefore, notonly an object of this portion of the invention to complete the dryingof the paper web 85 but also to rid these pockets of moisture laden air.In carrying this out, I provide air ducts 80 extending longitudinally ofthe Fourdrinier drier. The ducts 80 are provided with tuyeres 8| forinjecting heated air into and through the pockets,

paper web 88 and also ridding the pockets oi moisture laden air. Heatedair is delivered to the ducts 88 by means of branch duets l2 emanatingfrom a common duct 88 which receives heated air from a fan or blower 88,which may be driven in any suitable manner, such as by a pulley 8|.Heated air is delivered to the fan or blower 88 through a duct 88 from aradiator or heat exchanger 81 which receives a supply of heating iiuidsuch as steam from pipes 88. The volume of air delivered to the ducts88, and consequently the drying action of the air blast, may becontrolled by varying the speed of the fan 80, by a volume damper, or bymeans of a damper 88 which, for purposes of illustration, is shown to bea by-pass damper, the by-pass being afforded by a duct I88.

Referring specifically to Figure 3, with the bypass damper 88 in theposition shown, substantially-all of the air delivered by the fan isbeing forced into the pockets of the drier. As the damper 88 ispositioned towards the left, the supply-mi heatedair to the pockets isdecreased and i101: excess air is delivered into the by-pass duct Theby-pass damper 88 may be adiustably positioned by a proportioning motorIlli which receives a supply of power from line wires I02 and I08leading from some source of power, not shown. It may also be desired tocontrol the drying action of the air blast not only by controlling thevolume of air delivered, but also by controlling the temperature of thisair. If this mode of operation be desired, the supply of steam to I I05.This controller I88 may comprise a pivoted lever I09 carrying a tensionroll IIO and an ad-- justable biasing weight III. The lever I09 mayoperate sliders I I2 and Ill with respect to potentiometer coils Ill andH5. The potentiometer coil I and its associated slider II2 may beconnected by wires I I1, H8 and II! to the proportioning motor I05. Inlike manner, the potentiometer coil H5 and its associated slider 8 maybe connected by wires I20, |2I and I22 to the proportioning motor IOI.

As the moisture content of the paper web 55 leaving the Fourdrinierdrier increases, the sliders H8 and 2 are moved downwardly with respectto their potentiometer coils H5 and Ill to operate the proportioningmotors IOI and I05 to increase the volume of air being delivered to thepockets and also to increase the temperature thereof which increases thedrying action of the air. As the moisture content of the paper web 55decreases, the sliders H3 and 2 are moved upwardly with respect to thepotentiometer coils I I5 and I It to operate the proportioning motorsIOI and I05 to decrease the volume of air being delivered to the pocketsand to decrease the temperature thereof whereby the drying action of theair blast is decreased.

If it be desired to control only the temperature of the air and notcontrol the volume of the air, the damper 99 and the proportioning motorIII may be omitted and, likewise, if it be desired to control only thevolume of the air and not the temperature thereof, the proportioningmotor Ill may be omitted.

Ii'itbedesiredtoheatonlythat portion otthe air which is delivered to thetuyeres ll, a'heat exchanger or radiator Illa may be placed in the ductll between the by-pass damper ll and the branch ducts 0!. Heating fluidin the form of steam may be supplied to this heat exchanger lilo bysuitable pipes Illa and the supply of steam to the heat exchanger Illamay be controlled in exactly the same manner as the supply of steam tothe heat exchanger ll is controlled. This type of installation in someinstances may be more economical since heated air is not bypassed by theby-pass damper ll.

From the above it is seen that in this modiflcation, as in the previousmodifications, I have provided a means whereby the drying action of thedrying rolls is maintained substantially constant and that anyvariations in moisture content of the paper web leaving the drier aretaken care of by means of the air blast, the drying effect of this airblast being controlled in accordance with the moisture content of thepaper web. Therefore, an extremely simple and emcient control system isprovided whereby the moisture content of the paper web leaving thedriers is maintained substantially constant at all times. Also, it isseen that the majority of the drying action, which in this instance isaccomplished by the steam drier rolls, is maintained constant and thatvariations in the moisture content of the paper web are taken care of byonly adjusting a smaller portion of the drying action which, in thisinstance, is the air blast means. By reason of this mode of operation,an extremely sensitive control may be obtained. Further, in themodiflcation of Figures 2 and 3, I have not only provided an accuratecontrol system for controlling the moisture content of the paper web buthave also provided a means for ridding the pockets of a Fourdrinierdrier of moisture laden air whereby the drying action of the drier isextremely facilitated.

Although for purposes of illustration, I have shown various forms of myinvention, other forms thereof may become obvious to those skilled inthe art, and, consequently, my invention is to be limited only by thescope of the appended claims and prior art.

I claim as my invention:

1. In a drier of the class described for drying a substance, dryingmeans for accomplishing a major portion of the drying action, controlmeans responsive to the drying properties of said drying means formaintaining the drying action thereof substantially constant, otherdrying means for completing the drying action, and means responsive tothe moisture condition of the substance to vary said other drying meansto increase or decrease its drying action.

2. In a device of the class described for drying a substance, steamdrying means for accomplishing a portion of the drying action, meansresponsive to a heating property of the steam for maintaining the dryingaction thereof substantially constant, air drying means foraccomplishing the remainder of the drying action, and means responsiveto the moisture in the substance for controlling said air drying meanswhereby the substance is dried to a predetermined degree regardless ofits initial condition;

3. In a drier of the class described having drier roll means over whichthe substance to be dried is fed for accomplishing the drying action,the combination of air mm means also for accomplishing a drying action,control means responsive to the drying properties of the drier rollmeans for maintaining the drying action thereof substantially constant,and other control means responsive to the moisture condition of thesubstance for varying the drying action of the air blast means, both ofsaid control means coactlng to accomplish a drying action formaintaining the anal condition of the substance to be driedsubstantially constant regardless of its initial condition.

4. In a drier of the class described having steam drier roll means overwhich the substance to be I dried is fed for accomplishing a dryingaction,

the combination of control means responsive to a heating property of theheating medium supplying heat to the drier roll means for controllingthe supply of steam thereto for maintaining the drying action thereofsubstantially constant, hot air blast means also for accomplishing adrying action and comprising ducts, fan means and heat exchanger means,and other control means responsive to the moisture content of thesubstance for controlling the drying action of said air blast means tomaintain the final condition of the substance substantially constant.

5. In a drier of the class described having steam roll means over whichthe substance to be dried is fed for accomplishing a drying action, thecombination of control means responsive to a heating property of thesteam supplied to said steam roll means for controlling the supply ofsteam thereto for maintaining the drying action thereof substantiallyconstant, hot air blast means also for accomplishing a drying action andcomprising ducts, fan means and heat exchanger means, and other controlmeans responsive to the moisture content of the substance forcontrolling the heat content of said heat exchanger means whereby thedrying action of said hot air blast means is varied to maintain thefinal condition of the substance substantially constant.

6. In a drier of the class described having steam roll means over whichthe substance to be dried is fed for accomplishing a drying action, thecombination of control means responsive to a heating property of thesteam supplied to said steam roll means for controlling the supply ofsteam thereto for maintaining the drying action thereof substantiallyconstant, hot air blast means also for accomplishing a drying action andcomprising ducts, fan means, damper means and heat exchanger means, andother control means responsive to the moisture content of the substancefor controlling the operation of said damper means whereby the dryingaction of said hot air blast means is varied to maintain the finalcondition of the substance substantially constant.

7. In a drier for removing moisture from a substance, in combination,air blast means for causing a flow of air across the substance beingdried to accomplish a drying action, a controller for varying the dryingaction of said air blast drying means, motor means for positioning saidcontroller, a device responsive to the moisture content of the substancebeing dried, and means actuated by said device for controlling saidmotor means in a manner to increase the drying action of said air blastdrying means upon an increase in moisture content of the substance beingdried,- and to decrease the drying action upon a decrease in moisturecontent.

8. In a drier for removing moisture from a substance, in combination,air blast means for causing a flow of air across the substance beingdried to accomplish a drying action, a controller for varying the rateof air flow across the substance being dried to thereby vary the dryingaction of the air blast drying means, motor means for positioning saidcontroller, a device responsive to the moisture content of the substancebeing dried, and means actuated by said device for controlling saidmotor means in a manner to increase the rate of air flow over thesubstance being dried upon an increase in moisture content of thesubstance being dried, and to decrease the rate of air flow upon adecrease in moisture content.

9. In a drier for removing moisture from a substance, in combination,air blast means for causing a flow of air across the substance beingdried to accomplish a drying action, means including a controller forvarying the temperature of said air blast for thereby varying the dryingaction of said air blast drying means, motor means for positioning saidcontroller, a device responsive to the moisture content oi the substancebeing dried, and means actuated by said device for controlling saidmotor means in a manner to increase the temperature of said air blastupon an increase in moisture content of the substance being dried, andto decrease the air blast temperature upon a decrease in moisturecontent.

10. In a drier of the class described having steam roll means over whichthe substance to be dried is fed for accomplishing a drying action, thecombination of motor means for controlling the supply of steam to saidsteam roll means, a variable resistance operatively related to saidmotor means, means responsive to variations in a heating property ofsaid steam roll means for varying said resistance to control said motormeans proportionately to maintain the heat content of said steam rollmeans constant, air blast means also for accomplishing a drying action,motor means for controlling said air blast means, a variable resistanceoperatively associated therewith, and detector means responsive tovariations in the moisture condition of the substance for varying saidresistance to control said motor means proportionately whereby thedrying action of said air blast means is varied to maintain the finalcondition of said substance substantially 4 constant.

BUTCHER SKAGERBERG.

